Composite materials and process

ABSTRACT

Composite films and film laminates comprising at least one elastomeric core and a surrounding nonelastomeric matrix preferably prepared by coextrusion. The film when stretched and allowed to recover will create an elastomeric composite.

This application is a divisional of application Ser. No. 08/427,424,filed Apr. 24, 1995, now allowed, which is a continuation-in-partapplication of application Ser. No. 08/225,095, filed Apr. 8, 1994, nowU.S. Pat. No. 5,429,856, which is a continuation of application Ser. No.07/971,277, filed Nov. 4, 1992, now abandoned, which is acontinuation-in-part of application Ser. No. 07/501,331, filed Mar. 26,1990 now abandoned.

BACKGROUND AND FIELD OF THE INVENTION

The invention concerns coextruded elastic composites and structuresobtainable thereby.

Elastomeric materials have been long and extensively used in garments,both disposable and reusable. Conventionally, the elastic is stretchedand in this stretched condition attached to a substrate. Afterattachment, the elastic is allowed to relax which will generally causethe substrate to shirr or gather. Elastic was at one time applied bysewing, see, e.g., U.S. Pat. Nos. 3,616,770 (Blyther et al.), 2,509,674(Cohen), and 22,038. More recently, this procedure has been displaced bythe use of adhesive, e.g., U.S. Pat. No. 3,860,003 (Buell). Buellproposed the use of an elastic strand in the leg areas of the disposablediaper. Welding has also been proposed in U.S. Pat. No. 3,560,292(Butter) although sonic welding is preferred. A pivotal problem with allthese attachment methods has been how to keep the elastic in a stretchedcondition while applying it to the substrate. A solution has beenproposed in the use of heat shrink elastomeric materials, e.g., U.S.Pat. No. 3,639,917 (Althouse).

In diapers, for example, elastomeric bands are typically used in thewaistband portions such as discussed in U.S. Pat. No. 4,681,580 (Reisinget al.), and U.S. Pat. No. 4,710,189 (Lash). Both these patents describethe use of elastomeric materials which have a heat stable and a heatunstable form. The heat unstable form is created by stretching thematerial when heated around its crystalline or second phase transitiontemperature followed by a rapid quenching to freeze in the heat unstableextended form. The heat unstable elastomeric film can then be applied tothe, e.g., diaper and then heated to its heat stable elastomeric form.This will then result in a desirable shirring or gathering of thewaistband of the diaper. A problem with these materials, other thancost, is the fact that the temperature at which the material must beheated to release the heat unstable form is an inherent and essentiallyunalterable property of the material to be used. This inflexibility cancause problems. First, it is more difficult to engineer the othermaterials with which the waistband is associated so that they arecompatible with the temperature to which the elastomeric member must beheated in order to release the heat unstable form. Frequently thistemperature is rather high which can potentially cause significantproblems with the adhesive used to attach the elastomeric waistband, or,e.g., the protective back sheet or top sheet of the diaper. Further,once chosen the elastomer choice can constrain the manufacturing processrendering it inflexible to lot variations, market availability and costsof raw materials (particularly elastomer(s)), customer demands, etc.

A problem noted with the application of elastic to a diaper, as proposedin U.S. Pat. No. 3,860,003, resides in the proposed use of a singlerelatively large denier elastomeric ribbon. This ribbon will concentratethe elastomeric force in a relatively narrow line. This allegedly causedthe elastic to pinch and irritate the baby's skin. Proposed solutions tothis problem included the use of wider bands of elastic as per U.S. Pat.Nos. 4,352,355 (Mesek et al.) and 4,324,245 (Mesek et al.). Allegedly,this allows the contractive forces to be distributed over a wider areaand prevents irritation of the baby's skin. The preferred elastomerproposed in these applications are films of A-B-A block copolymers witha thickness of 0.5 to 5 mils. Problems noted with these films are thatthey are difficult to handle and must be applied with relativelycomplicated stretch applicators as per U.S. Pat. Nos. 4,239,578 (Gore),4,309,236 (Teed), 4,261,782 (Teed), and 4,371,417 (Frick et al.).

An alternative solution to the pinching problem of U.S. Pat. No.3,860,003 is proposed in the use of multiple strands of relatively smalldenier elastic, as per U.S. Pat. No. 4,626,305 (Suzuki et al), whodescribes the use of three to 45 fine rubber strings to elasticize adiaper. However, to keep the bands properly aligned they are preferablyfused together. The alleged advantage in this method is that a smallnumber of narrow elastic bands can be stretched at a high ratio to givethe same tensile stress that a single equivalent diameter elastic bandwould yield at a lower stretch ratio. Accordingly, the stress can bedistributed over a wider area and less elastic needs to be used (i.e.,as the elastic is stretched more when applied). A similar approach isproposed by U.S. Pat. No. 4,642,819 (Ales et al.). However, Ales et al.uses larger denier elastic bands which act as backup elastic seals foreach other when or if the diaper is distorted during use. A variation ofthis approach is proposed in U.S. Pat. No. 4,300,562 (Pieniak). Pieniakuses a series of interconnected elastomeric strands, in a reticulateform. Wider strands are positioned to engage the narrow portion of atapered surface. This allegedly results in a more even distribution ofstress over where the reticulate elastic engages the tapered surface.Although the use of multiple strands of elastic materials hasadvantages, they are more difficult to incorporate into a garment in aspaced coordinated fashion. Thin elastic strands have a tendency towander and further present a thin profile making adhesion to the garmentsubstrate difficult.

Spaced elastic elements are provided other than by multiple elasticstrands. For example, it has been proposed to provide regionalizedelastic in the waistband portion of a disposable diaper in U.S. Pat. No.4,381,781 (Sciaraffin).

Regionalized elastic is also placed in diaper adhesive fastening tabs asper U.S. Pat. Nos. 4,389,212 (Tritsch), 3,800,796 (Jacob), 4,643,729(Laplanche), 4,778,701 (Pape) and 4,834,820 (Kondo et al.). Thesepatents are directed to different composite structures designed to yielda fastening tab with an elasticized central portion and inelastic orrelatively rigid end portions for attachment to either side of a garmentclosure. These composites are quite complicated and generally are formedby adhering several separate elements together to provide theelasticized central region.

Elastomers used in these structures also exhibit relatively inflexiblestress/strain characteristics which cannot be chosen independently ofthe activation temperature. Materials with a high modulus of elasticityare uncomfortable for the wearer. Problems with a relatively stiff orhigh modulus of elasticity material can be exaggerated by thecoefficient of friction and necking of the elastomer which can cause thematerial to bite or grab the wearer.

In copending application Ser. No. 07/438,593, filed Nov. 17, 1989, nowU.S. Pat. No. 5,501,629, having a common assignee, there is disclosed amulti-layer elastic laminate having at least one elastomeric layer andat least one coextensive skin layer which addresses certain of the abovenoted problems in the art. In addition, the laminate has extremelyuseful and novel properties. When cast, or after formation, the elasticlaminate is substantially inelastic. Elasticity can be imparted to theinelastic form of the laminate by stretching the laminate, by at least aminimum activation stretch ratio, wherein an elastic laminate materialwill form immediately, over time or upon the application of heat. Themethod by which the elastic laminate material is formed can becontrolled by a variety of means. After the laminate has been convertedto an elastomeric material, there is formed a novel texture in the skinlayer(s) that provides significant advantages to the laminate. Despitethe numerous advantages in the materials of the copending application,there is room for improvement for some applications such as thosediscussed above. For example, where intermittent elasticized regions aredesired such as in a diaper fastening tab or where it is desirable tohave discrete adjacent longitudinal bands of elastic. In theseapplications, laminated plastic films are less desirable. For example,they must be assembled into complex composite structures as discussedabove to provide regionalized elastic. Therefore, it is desirable toretain the advantages of the material disclosed in the copendingapplication while providing structures having regionalized elastic areasor elastic bands which can be simply constructed and are also moreresistant to delamination than multi-layer laminate structures.

SUMMARY OF THE INVENTION

The present invention relates to improved non-tacky, nonelastic materialcapable of becoming elastomeric when stretched. The material of thepresent invention is comprised both of an elastomeric polymeric coreregion, which provides the elastomeric properties to the material and apolymeric matrix, which is capable of becoming microtextured atspecified areas. The microtextured areas will correspond to sections ofthe material that have been activated from an inelastic to anelastomeric form. In preferred embodiments of the present invention, thematrix material further can function to permit controlled recovery ofthe stretched elastomer, modify the modulus of elasticity of theelastomeric material and/or stabilize the shape of the elastomericmaterial (e.g., by controlling further necking). The material ispreferably prepared by coextrusion of the selected matrix andelastomeric polymers. The novel, non-tacky microtextured form of thematerial is obtained by stretching the material past the elastic limitof the matrix polymer in predetermined elastic containing regions. Thelaminate then recovers in these predetermined regions, which can beinstantaneous, over an extended time period, which is matrix materialcontrollable, or by the application of heat, which is also matrixmaterial controllable.

In certain constructions, complex periodic macrostructures can formbetween selectively elasticized regions depending on the method anddirection of stretch activation. This can result in elastics with aconsiderable degree of bulk formed with relatively small amounts ofelastic. This is desirable for many applications, particularly ingarments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1(a)-(i) are cross-sectional segments of extruded laminates of theinvention before microstructuring.

FIG. 2 is a schematic representation of a modified combining adapterused to form the invention material.

FIG. 3 is a schematic representation of a process and apparatus used tocoextrude the laminates of the invention.

FIG. 4 is a schematic of the microstructure formed in the elastomericregions of the invention film material that has been uniaxiallystretched.

FIG. 5 is a schematic representation of a tape tab formed of theinvention film material.

FIG. 6 is a scanning electron micrograph (100×) of a film material thathas been uniaxially stretched transverse to the extruder machinedirection.

FIG. 7 is a scanning electron micrograph (100×) of the film material ofFIG. 5 uniaxially stretched in the machine direction showing periodicmacrostructure folding.

FIG. 8 is a scanning electron micrograph(1000×) of a film materialuniaxially stretched in the machine direction showing periodicmacrostructure folding.

FIG. 9 is a cutaway top view of a tape tab cut from a roll of theinvention film material.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

The present invention relates broadly to novel non-tacky nonelasticmaterials capable of becoming elastic when stretched comprising at leastone elastomeric core region surrounded by a relatively nonelastomericmatrix. Selected regions containing the elastomeric core regions arestretched beyond the elastic limit of the surrounding matrix material.The deformed matrix is then relaxed with the core forming an elasticregion having a microstructured matrix skin layer. Microstructure meansthat the matrix skin layer contains peak and valley irregularities orfolds which are large enough to be perceived by the unaided human eye ascausing increased opacity over the opacity of the laminate beforemicrostructuring, and which irregularities are small enough to beperceived as smooth or soft to human skin. Magnification of theirregularities is usually required to see the details of themicrostructured texture.

Typical constructions of the invention film material 1 are shown in FIG.1(a)-(i) where 2 designates the elastomeric core and 3 the matrixmaterial. FIG. 1 is an edge view of the material as it is formed,preferably by a coextrusion process. The material is preferably in afilm form. Matrix skin layers 4 and 5 in conjunction with the thicknessof the core material 6 determines the performance of the material, e.g.,the shrink mechanism, the microstructure, etc. The nonelastomercontaining matrix region or field 7 will not recover when stretchedexcept by gathering into periodic folds between parallel recoveringelastic core containing regions.

The elastomer can broadly include any material which is capable of beingformed into thin films and exhibits elastomeric properties at ambientconditions. Elastomeric means that the material will substantiallyresume its original shape after being stretched. Further, preferably,the elastomer will sustain only small permanent set followingdeformation and relaxation which set is preferably less than 20 percentand more preferably less than 10 percent of the original length atmoderate elongation, e.g., about 400-500%. Generally, any elastomer isacceptable which is capable of being stretched to a degree that willcause permanent deformation in a relatively inelastic skin layer of thematrix material over the elastomer. This can be as low as 50%elongation. Preferably, however, the elastomer is capable of undergoingup to 300 to 1200% elongation at room temperature, and most preferablyup to 600 to 800% elongation at room temperature. The elastomer can beboth pure elastomers and blends with an elastomeric phase or contentthat will still exhibit substantial elastomeric properties at roomtemperature.

As discussed above, heat-shrinkable elastics have received considerableattention due to the ability to fabricate a product using the unstablestretched elastomer at ambient conditions and then later applying heatto shirr the product. Although these elastomers are contemplated for usein the present invention, other non-heat-shrinkable elastomers can beused while retaining the advantages of heat shrinkability with the addeddimension of the possibility of substantially controlling the heatshrink process. Non-heat-shrinkable means that the elastomer, whenstretched, will substantially recover sustaining only a small permanentset as discussed above. Therefore, the elastomeric core(s) can be formedfrom non-heat-shrinkable polymers such as block copolymers which areelastomeric such as those known to those skilled in the art as A-B orA-B-A block copolymers. These block copolymers are described, forexample, in U.S. Pat. Nos. 3,265,765; 3,562,356; 3,700,633; 4,116,917and 4,156,673, the substance of which are incorporated herein byreference. Styrene/isoprene, butadiene or ethylene- butylene/styrene(SIS, SBS or SEBS) block copolymers are particularly useful. Otheruseful elastomeric compositions can include elastomeric polyurethanes,ethylene copolymers such as ethylene vinyl acetates, ethylene/propylenecopolymer elastomers or ethylene/propylene/diene terpolymer elastomers.Blends of these elastomers with each other or with modifyingnon-elastomers are also contemplated. For example, up to 50 weightpercent, but preferably less than 30 weight percent, of polymers can beadded as stiffening aids, such as polyvinylstyrenes, polystyrenes suchas poly(alpha-methyl)styrene, polyesters, epoxies, polyolefins, e.g.,polyethylene or certain ethylene/vinyl acetates, preferably those ofhigher molecular weight, or coumarone-indene resin. The ability to usethese types of elastomers and blends provides the invention filmmaterial with significant flexibility.

Viscosity reducing polymers and plasticizers can also be blended withthe elastomers such as low molecular weight polyethylene andpolypropylene polymers and copolymers, or tackifying resins such asWingtack™, aliphatic hydrocarbon tackifiers available from GoodyearChemical Company. Tackifiers can also be used to increase theadhesiveness of an elastomeric core(s) to the matrix material. Examplesof tackifiers include aliphatic or aromatic liquid tackifiers, aliphatichydrocarbon resins, polyterpene resin tackifiers, and hydrogenatedtackifying resins. Aliphatic hydrocarbon resins are preferred. Additivessuch as dyes, pigments, antioxidants, antistatic agents, bonding aids,antiblocking agents, slip agents, heat stabilizers, photostabilizers,foaming agents, glass bubbles, starch and metal salts for degradabilityor microfibers can also be used in the elastomeric core layer(s).Suitable antistatic aids include ethoxylated amines or quaternary aminessuch as those described, for example, in U.S. Pat. No. 4,386,125(Shiraki), who also describes suitable antiblocking agents, slip agentsand lubricants. Softening agents, tackifiers or lubricants aredescribed, for example, in U.S. Pat. No. 4,813,947 (Korpman) and includecoumarone-indene resins, terpene resins, hydrocarbon resins and thelike. These agents can also function as viscosity reducing aids.Conventional heat stabilizers include organic phosphates, trihydroxybutyrophenone or zinc salts of alkyl dithiocarbonate. Suitableantioxidants include hindered phenolic compounds and amines possiblywith thiodipropionic acid or aromatic phosphates or tertiary butylcresol, see also U.S. Pat. No. 4,476,180 (Wnuk) for suitable additivesand percentages.

Short fibers or microfibers can be used to reinforce the elastomericcore(s) for certain applications. These fibers are well known andinclude polymeric fibers, mineral wool, glass fibers, carbon fibers,silicate fibers and the like. Further, certain particles can be used,including carbon and pigments.

Glass bubbles or foaming agents are used to lower the density of theelastomeric layer and can be used to reduce cost by decreasing theelastomer content. These agents can also be used to increase the bulk ofthe elastomer. Suitable glass bubbles are described in U.S. Pat. Nos.4,767,726 and 3,365,315. Foaming agents used to generate bubbles in theelastomer include azodicarbonamides. Fillers can also be used to someextent to reduce costs. Fillers, which can also function as antiblockingagents, include titanium dioxide and calcium carbonate.

The matrix can be formed of any semi-crystalline or amorphous polymerthat is less elastic than the core(s) and will undergo permanentdeformation at the stretch percentage that the elastomeric core(s) willundergo. Therefore, slightly elastic compounds, such as some olefinicelastomers, e.g., ethylene-propylene elastomers orethylene-propylene-diene terpolymer elastomers or ethylenic copolymers,e.g., ethylene vinyl acetate, can be used as matrix materials, eitheralone or in blends. However, the matrix is generally a polyolefin suchas polyethylene, polypropylene, polybutylene or apolyethylene-polypropylene copolymer, but may also be wholly or partlypolyamide such as nylon, polyester such as polyethylene terephthalate,polyvinylidene fluoride, polyacrylate such as poly(methylmethacrylate)(only in blends) and the like, and blends thereof. Thematrix material can be influenced by the type of elastomer selected. Ifthe elastomeric core is in direct contact with the matrix the matrixshould have sufficient adhesion to the elastomeric core(s) such that itwill not readily delaminate. Where a high modulus elastomeric core(s) isused with a softer polymer matrix, a microtextured surface may not form.

Additives useful in the matrix include, but are not limited to, mineraloil extenders, antistatic agents, pigments, dyes, antiblocking agents,provided in amounts less than about 15%, starch and metal salts fordegradability and stabilizers such as those described for theelastomeric core(s).

Other layers may be added between the core(s) and the matrix such as tielayers to improve bonding, if needed. Tie layers can be formed of, orcompounded with, typical compounds for this use including maleicanhydride modified elastomers, ethyl vinyl acetates and olefins,polyacrylic imides, butyl acrylates, peroxides such as peroxypolymers,e.g., peroxyolefins, silanes, e.g., epoxysilanes, reactive polystyrenes,chlorinated polyethylene, acrylic acid modified polyolefins and ethylvinyl acetates with acetate and anhydride functional groups and thelike, which can also be used in blends or as compatiblizers in one ormore of the matrix or core(s). Tie layers are sometimes useful when thebonding force between the matrix and core is low, although the intimatecontact between skin and matrix should counteract any tendency todelaminate. This is often the case with a polyethylene matrix as its lowsurface tension resists adhesion.

One unique feature of the invention is the ability to control the shrinkrecovery mechanism of the film depending on the conditions of filmformation, the nature of the elastomeric core(s), the nature of theskin(s), the manner and direction in which the film is stretched and therelative thicknesses of the elastomeric core and the matrix skinlayer(s) over the core(s). By controlling these variables, in accordancewith the teaching of this invention, the film material can be designedto instantaneously recover, recover over time or recover upon heatactivation.

A film material capable of instantaneous shrink recovery is one in whichthe stretched elastomeric material will recover more than 15% (of thetotal recovery available) in 1 sec. A film capable of time shrink is onewhere the 15% recovery point takes place more than 1 sec., preferablymore than 5 sec., most preferably more than 20 sec. after stretch, and afilm capable of heat shrink is where less than 15% shrink recoveryoccurs to the laminate in the first 20 seconds after stretch. Percentrecovery of the elastomeric core containing region is the percent thatthe amount of shrinkage is of the stretched length minus the originallength of the elastomeric core containing region. For heat shrinkmaterials, there will be an activation temperature which will initiatesignificant heat activated recovery. The activation temperature used forheat shrink recovery will generally be the temperature that will yield50% of the total possible recovery (T_(a-50)) and preferably thistemperature is defined as the temperature which will yield 90%(T_(a-90)) of the total possible recovery. Total possible recoveryincludes the amount of preactivation shrinkage.

Generally, where the matrix skin layers 4 and 5 over the core(s) in thepreferential activation region are on average relatively thin, the filmmaterial will tend to contract or recover immediately after stretched.When the matrix skin thickness 4 and 5 is increased sufficiently, thefilm material can become heat shrinkable in the activated regions. Thisphenomenon can occur even when the elastomeric core(s) is formed from anon-heat shrinkable material. By careful selection of the thicknesses ofthe elastomeric core 2 and the matrix skin layer(s) 4 and 5, thetemperature at which the material recovers by a set amount can becontrolled within a set range. This is termed skin controlled recovery,where generally by altering the thickness or composition of the matrixskins 4 and 5(assuming a constant matrix width in the noncore containingregion for longitudinal activation), one can raise the elastic recoveryactivation temperature of an elastomeric core 2 by a significant degree,generally more than at least 10° F. (5.6° C.) and preferably by 15° F.(8.3° C.) and more. Although any matrix skin thickness which iseffective can be employed, too thick a matrix skin 4 and 5 will causethe material to remain permanently set when stretched. Generally wherean average single matrix skin is less than 30% of the film in thisregion, this will not occur although more complex retraction can beexpected where the elastomeric core aspect ratio is small (e.g., a roundcore as per FIG. 1(a)). For most heat or time shrink materials, thestretched and activated regions of the film material must be cooled sothat the energy released during stretching does not cause immediate heatactivated elastic recovery. Fine tuning of the shrink recovery mechanismcan be accomplished by adjusting the degree to which the activatedregions are stretched. The more stretch, the more the film will tend toinstantaneously recover.

This overall control over the shrink recovery mechanism of the activatedregions of the elastic or elastomeric film material discussed abovecoupled with the ability to control the amount of stretch needed toactivate elastic regions of the film material are extremely importantadvantages.

This control permits adjustment of the activation and recovery mechanismof the elastomeric film to fit the requirements of a manufacturingprocess thereby avoiding the need to adjust a manufacturing process tofit the shrink recovery mechanism of a particular elastomer.

One is also able to use skin controlled recovery to control the slow ortime shrink recovery mechanism, as with the heat shrink mechanism. Thisshrink recovery mechanism occurs as an intermediate between instant andheat shrink recovery. Skin layer and stretch ratio control is possibleas in the heat shrink mechanism, with the added ability to change theshrink mechanism in either direction, i.e., toward a heat or an instantshrink elastic film material.

A time shrink recovery film material will also exhibit some heat shrinkcharacteristics and vice versa. For example, a time shrink film can beprematurely recovered by exposure to heat, e.g., at a time prior to 20seconds after stretch.

Recovery can also be initiated for most time shrink and some lowactivation temperature heat shrink recovery film materials by mechanicaldeformation or activation. In this case, the film is scored, folded,wrinkled, or the like in the core containing regions to cause localizedstress fractures that cause localized premature folding of the skin,accelerating formation of the recovered microtextured film. Mechanicalactivation can be performed by any suitable method such as by using atextured roll, a scoring wheel, mechanical deformation or the like.

Additives to the core discussed above can significantly affect theshrink recovery mechanism. For example, stiffening aids such aspolystyrene can shift an otherwise heat shrinkable material into a timeor instant shrink material. However, the addition of polypropylene orlinear low density polyethylene (less than 15%) to astyrene/isoprene/styrene block copolymer core resulted in exactly theopposite effect, namely transforming time or instant shrink materials toheat shrink or no shrink materials. However, the possibility ofpolyolefin use in the elastomeric core is significant from a processingstandpoint in permitting limited recycling of off batches and polyolefinadditives can lower extruder torque.

A further unique feature of the present invention lies in the ability tosignificantly reduce the coefficient of friction (C.O.F.) of theactivated regions of the elastic film material. The microtexturing isthe major factor contributing to this C.O.F. reduction which, asdiscussed above, is controllable not only by the manner in which thefilm is stretched but also by the degree of stretch, the overall filmthickness, the core and matrix compositions and the core to skin ratio.C.O.F. and the core/skin ratio are related such that as the ratioincreases the C.O.F. decreases. Thus, fine texture yields lower C.O.F.values. Preferably, the C.O.F. will be reduced by a factor of 0.5 andmost preferably by at least a factor of 0.1 of the microtextured film toitself, in the direction of stretch, when a microstructured surface isformed in accordance with the invention, as compared to the as castfilm. This ability to reduce C.O.F. contributes to a softer texture andfeel for the film, which is desirable for use in the medical and apparelfields.

Writability of the film in the activated region is also increased by themicrostructured surface that results when the stretched film recovers.Either organic solvent or water-based inks will tend to flow into themicrostructured surface channels and dry there. The more viscous the inkthe less it will tend to wick in the microchannels of the surface andhence bleed. Similarly, the more the surface attraction between the skinlayer and the ink, the better will be the writing characteristics of themicrostructured surface. The writing surface characteristics of the filmcan also be altered with conventional additive or surface treatmenttechniques to the extent that they do not interfere with microtexturing.

The overall structure of the present invention film material may beformed by any convenient matrix forming process such as by pressingmaterials together, coextruding or the like, but coextrusion is thepresently preferred process for forming a material with elastomericcores within a relatively nonelastomeric material matrix. Coextrusionper se is known and is described, for example, in U.S. Pat. Nos.3,557,265 (Chisholm et al), 3,479,425 (Leferre et al.), and 3,485,912(Schrenk et al). Tubular coextrusion or double bubble extrusion is alsopossible for certain applications. The core and matrix are typicallycoextruded through a specialized die and feedblock that will bring thediverse materials into contact while forming the material.

The composite film materials shown in FIG. 1 can be formed, for example,by the apparatus described in Schrenk et al. Schrenk et al. employs asingle main orifice and polymer passageway die. In the main passageway,which would carry the matrix material, is a nested second housing havinga second passageway. The second passageway would have one or moreoutlets, each defining an elastomeric core, which discharges matrixmaterial flowstreams into the main passageway matrix flow region. Thiscomposite flow then exits the orifice of the main passageway.

Another advantageous coextrusion process is possible with a modifiedmultilayer, e.g., a three-layer, die or combining adapters such as madeby Cloeren Co., Orange, Tex. Combining adapters are described in U.S.Pat. No. 4,152,387(Cloeren) discussed above. Streams of thermoplasticmaterials flowing out of extruders, or from a specialized multilayerfeedblock, at different viscosities are separately introduced into thedie or adapter, and the several layers exiting the flow restrictionchannels converge into a melt laminate. A suitably modified Cloeren typeadapter 10 is shown in FIG. 2(a) and (b). Three separate polymer flowstreams, 11, 12 and 13 are separated and regulated by veins 15 and 16.Streams 11 and 13 are of the matrix polymer(which in this case may bedifferent polymers) while stream 12 is the elastomeric core polymericmaterial. Flow 12 is intercepted by insert 14 with cutouts 17, which canbe the same or different size, which permits passage of elastomericmaterials. The insert is generally attached to one vane and snugglyengaged with the second to allow the vanes to rotate in unison. Thisallows adjustment of the core material position within the matrix.Streams 11, 13 and the flow from stream 12 through cutouts 17 convergeand form the invention film material(a five layer combining adapter isalso useable to incorporate tie layers in the matrix. The combiningadapter is used in conjunction with extruders, optionally in combinationwith multilayer feedblocks, supplying the thermoplastic materials. Sucha scheme for producing the present invention film material is shownschematically in FIG. 3, for a three layer adapter, to form basicmaterials such as those shown in FIG. 1. AA, BB, and CC are extruders.AA', BB' and CC' are streams of thermoplastic material flowing into thefeedblock or manifold die. D is the 3 or more (e.g., 5-layer) layerfeedblock. E is the die and/or combining adapter, F is a heated castingroll, and G and H are rolls to facilitate take-off and roll-up of thefilm material.

The die and feedblock used are typically heated to facilitate polymerflow and layer adhesion. The temperature of the die depends upon thepolymers employed and the subsequent treatment steps, if any. Generallythe temperature of the die is not critical but temperatures aregenerally in the range of 350° to 550° F. (176.7° to 287.8° C.) with thepolymers exemplified.

The invention film material has an unlimited range of potential widths,the width limited solely by the fabricating machinery width limitations.This allows fabrication of zone activatable microtextured elastic filmsfor a wide variety of potential uses.

The regionally elasticizable film material formed in accordance with theinvention will have longitudinal bands of elastomeric material in amatrix of relatively nonelastomeric material. When this structure isstretched a microstructured surface will form in the matrix skin regions4 and 5 of FIG. 1. This is shown in FIGS. 6 and 7 for transverse (to themachine direction) and longitudinal stretching and relaxing,respectively. Regions or fields 7 between the elastomeric cores 2, whenthe film is stretched longitudinally (i.e. in the machine direction),will gather into folds, as shown in FIGS. 7 and 8 for two differentfilms. These folds will be several orders of magnitude larger than themicrotexture on skin regions 4 and 5. This can add significant amountsof volume to the elastic film, a desirable quality for use in garmentsand for certain protective packaging. The longitudinally stretchedmatrix material will also contribute to the recovery mechanism of thefilm so stretched.

The fold structure in regions 7 will depend on the spacing betweenadjacent elastomeric bands 2 and the degree to which the film isstretched and recovered, as seen in FIGS. 7 and 8 above. Foldssuperimposed on a microstructured surface is possible with structuressuch as 1(b), (h) and (i) where multiple or irregular elastic corescould lead to differing levels of recovery across the film. Theseembodiments would yield differing microstructures across the filmsurface as well as folds in lower recovery areas between areas of higherrecovery.

When the invention film material is stretched transversely to theelastomeric core bands (i.e., in the cross direction), the material willstretch in the regions containing the elstomeric cores 2 and possibly innonelasticized regions 7. However, region 7 should generally yield afterthe elasticized regions, due to the general lower modulus of theelastomeric material 2, as per FIG. 6. However, if regions.7 have asignificantly lower caliper than the elastomer containing regions, dueto die swell and flow characteristics, region 7 may yield with or priorto the elastomeric core containing regions. When nonelastomer containingregions 7 stretch, they will not recover, therefore increasing thedistance between the elastomeric bands, which will recover in thedirection of stretch as discussed elsewhere. Activation can also bepreferential in areas having higher elastomer content. For example, inFIG. 1(h) the film would tend to elongate preferentially in regionswhere there is an overlap in elastomeric cores or bands 2.

FIG. 4 is a schematic diagram of the common microstructure dimensionswhich are variable for uniaxially stretched and recovered films in theactivated regions. The general texture is a series of regular repeatingfolds. These variables are the total height A-A', the peak-to-peakdistance B-B', and the peak-to-valley distance C-C'.

Multiaxially stretching may be desirable where a more complexmicrostructure is desired. Biaxially, e.g., stretching creates uniquesurfaces while creating a film which will stretch in a multitude ofdirections and retain its soft feel.

It has also been found that the fold period of the microstructuredsurface is dependent on the core/skin ratio. This is, again, anotherindication of the control possible by careful choice of the parametersof the present invention.

When the film is stretched first in one direction and then in a crossdirection, the folds formed on the first stretch become buckled foldsand can appear worm-like in character with interspersed cross folds.Other textures are also possible to provide various folded or wrinkledvariations of the basic regular fold. When the film is stretched in bothdirections at the same time, the texture appears as folds with lengthdirections that are random. Using any of the above methods ofstretching, the surface structure is also dependent, as stated before,upon the materials used, the thickness of the layers, the ratio of thelayer thicknesses and the stretch ratio. For example, the extrudedmulti-layer film can be stretched uniaxially, sequentially biaxially, orsimultaneously biaxially, with each method giving a unique surfacetexture and distinct elastomeric properties.

The degree of microtexturing of elastic laminates prepared in accordancewith the invention can also be described in terms of increase in skinsurface area. Where the film shows heavy textures, the surface area willincrease significantly. Generally, the microtexturing will increase thesurface area by at least 50%, preferably by at least 100% and mostpreferably by at least 250%. The increase in surface area directlycontributes to the overall texture and feel of the film surface.

Increased opacity of the matrix skin also results from themicrotexturing. Generally, the microtexturing will increase the opacityvalue of a clear film to at least 20%, preferably to at least 30%. Thisincrease in opacity is dependent on the texturing of the skin regionswith coarse textures increasing the opacity less than fine textures. Theopacity increase is also reversible to the extent that when restretched,the film will clear again.

With certain constructions, the underlying elastomer may tend to degradeover time. This tendency may particularly occur with ABA blockcopolymers. Residual stress created during the stretching and recoverysteps of activating the material to its elastomeric form can acceleratethis process significantly. For those constructions prone to suchdegradation, a brief relaxing or annealing following activation may bedesirable. The annealing would generally be above the glass transitionpoint temperature (T_(g)) of the elastomer, above the B block T_(g) forABA block copolymers, but below the skin polymer melting point. A lowerannealing temperature is generally sufficient. The annealing willgenerally be for longer than 0.1 seconds, depending on the annealingtemperature. With commercial ABA block copolymers (e.g., Kraton™ 1107)an annealing or relaxing temperature of about 75° C. is found to besufficient.

The film formed in accordance with the above description of theinvention will find numerous uses due to the highly desirable propertiesobtainable. For example, the microtexture and macrostructures give theelastic film material a soft and silky feel as well as increased bulk.However, the softness of the elastic film, and strength in the elasticregions, can be advantageously increased by laminating a fibrous web, orother layer, to the film. This lamination is enhanced by thenonelasticized regions 7, which do not form a microstructure therebyenhancing adhesion between the elastic film and the fibrous web or thelike, also forming a suitable surface for coating an adhesive orattaching a mechanical fastener element. In the elastomeric core 2containing region(s), a fibrous web laminated to the elastic film canalso limit extensibility of the elastic core 2 containing regions.Preferably, the fibrous web is a nonwoven web such as a consolidated orbonded carded web, a meltblown web, a spunbond web, a spunlace web orthe like. The fibrous web is preferably bonded or laminated to the filmby adhesives, thermobonding, ultrasonic welding or the like when atleast the nonelastic regions 7 are substantially flat, e.g., prior tostretching or while stretching the film, for longitudinal and transversestretching, where the elastic activated portions of the film laminatecan further be non-necking. The fibrous web can also be attached afterstretching and recovering the elastic film for transverse stretchedwebs. Alternatively, the invention film can be directly extruded ontoone or two fibrous webs. The fibrous web must be extensible whenattached to the film prior to stretching the film and preferably thefibrous web will not fully recover when stretched with the film suchthat the fibrous web will form pleats in the elastic region when theelastic region recovers.

Transverse stretched nonwoven film laminates are particularlyadvantageous in that they will be substantially flat and elastic in onedirection and nonextensible, under typical tensioning forces used indiaper and like web assembly production lines, in the oppositedirection. This makes these laminates particularly advantageous where asoft one directional elastic is needed, such as a training pant sidepanel. Longitudinally stretched nonwoven film laminates are lessdesirable in these uses in that they are not flat, have less resistanceto extensibility in the nonelastic direction and can not be handledeasily by longitudinally unwinding from a roll.

The elastic film or film laminate can be extensively used in disposablediapers, for example as a waistband, located in either the front or sideportions of the diaper at waist level, as leg elastic or in adjustableslip-on diapers, where the elastic film could be used as, or in, sidepanels around the hip that have zones of elasticity to create a tightfitting garment. The films or film laminates can be applied ascontinuous or intermittent lengths by conventional methods. Whenapplied, a particular advantage of the elastic film is the ability touse thin zones of elastomers with high stretch ratios while activationof the elastic film can occur at a controlled stretch ratio(particularly when stretching transverse to the elastic bandlongitudinal direction), depending on the size of the elastomeric corecontaining regions, their activation stretch ratio and modulus behavior.

When used to provide intermittent zones of elasticity the film materialor a film laminate formed by, e.g., coextrusion can be cut laterallyinto strips containing portions of one or more elastomeric cores orbands. The elastic containing region(s) will be spaced by proper choiceof the widths of nonelastic regions 7 and elastomeric core(s) 6. Theelastic portion of the film or film laminate can thus be placed at theproper location to be elasticized in the finished article, see e.g.,U.S. Pat. No. 4,381,781 (diaper waistbands). The elastic film orlaminate could also be properly placed for diaper legbands, e.g., in adiaper "backsheet". The elastomeric cores 2 would be coextruded atlocations proper for elasticizing the leg regions with liquidimpermeable thermoplastic therebetween forming the diaper backsheet.

Another use for the invention film material, or film laminate, would beas an elasticized diaper fastening tab as per, e.g., U.S. Pat. No.3,800,796, and shown in FIG. 5. The one or more(not shown) elastomericcore(s) 2, e.g., could be placed at the desired location while providingnonelastic end portions 7. The elasticized film is preferably 10 to 50mm wide for most conventional tape tab constructions. This providesadequate tension without having to stretch the tape too far onto thediaper front. This tab could be cut from film stock containing one ormore elastomeric bands 2. Adhesive 8 or a mechanical fastener (e.g.,hook or loop) element could then be applied to one or more faces of thenonelastic end portions 7. However, the pressure-sensitive adhesivecoated(or mechanical fastener containing, not shown) end portion 27 forreleasable attaching to the diaper front portion could be 8 to 15 mmwide while the end portion 29 permanently attached to the diaper side iswidened substantially, as shown in FIG. 9 and disclosed in U.S. Pat. No.5,399,219.

In the form shown in FIG. 9 the tabs are cut from a continuous film orfilm laminate roll of stock material with one or more elastomeric bands22. The two ends, 27 and 29, are inelastic and preferable both coatedwith a pressure-sensitive adhesive 28. The tab form shown in FIG. 9would result in no waste (end portion 27 is an inverted mirror image ofend portion 29), however, other shapes or tab designs are possible whereinelastic end portion 29 may or may not be adhesive coated. In theembodiment of FIG. 9, the elastics forces are distributed to a wide areaalong the diaper side where end 29 is attached, which results in a morestable securement and better fit resulting from wider distribution ofthe elastic forces along the side portion of the diaper. Generally forthe embodiment of FIG. 9 and like tab forms, the terminal portion of end29 is at least twice as wide as the terminal portion of end 27 with agradual tapering in the elastic region therebetween.

An additional advantage with forming fastening tabs of the inventionelastic film or film laminate, is the versatility available. The tabscould be sold unstretched and easily activated by the customer,alternatively the tab could be applied stretched and activated, in bothcases the tacky rubber will not be exposed. An additional advantage witha stretched and activated film tab is that the activated regions willhave a surface microstructure which will tend to release adhesive tapeat lower application pressures. This feature can be used to form tabswith a desirable, centrally located, mechanical low adhesion backsizeregion, which is desirable for fastening tabs such as those disclosed inU.S. Pat. No. 4,177,812 (Brown et al.).

Garments often are shirred to give a snug fit. This shirring can beeasily obtained by applying heat shrink film materials while in anunstable stretched condition and then affecting the shirr by applicationof heat. The elastic film material(s) can be adhered to the garment byultrasonic welding, heat sealing and adhesives by conventional methods.Adherence would be preferably in the matrix regions 7.

The controlled relaxation obtainable by adjusting the layer ratios,stretch ratio and direction, and layer composition makes the elasticfilm of the invention well suited to high speed production processeswhere heat activated recovery can be controlled easily by hot fluidssuch as hot air, microwaves, UV radiation, gamma rays, frictiongenerated heat and infrared radiation. With microwaves, additives, suchas iron whiskers, aluminum flakes or nickel powder, may be needed toensure softening of the skin to effect skin controlled recovery.

The counter-balancing of the elastic modulus of the elastomeric core andthe deformation resistance of the matrix material also modifies thestress-strain characteristics of the activated regions of the filmmaterial. The modulus therefore can be modified to provide greaterwearer comfort when the film material is used in a garment. For example,a relatively constant stress-strain curve can be achieved. Thisrelatively constant stress-strain curve can also be designed to exhibita sharp increase in modulus at a predetermined stretch percent. Thenon-activated or non-stretched film as such is easier to handle and muchbetter suited to high speed production processes than would be aconventional elastic.

The composite elastic film or film laminate is also extremely wellsuited for use as a tape backing providing a high loft elastic tape withexcellent oxygenation resistance, tearability, self-adhesiveness andrepositionability to flat surfaces. The increased tearability isadvantageous in applications where each elastic strand is appliedseparately to a substrate such as a garment. In such garmentapplications, the tape can be readily torn between the elasticstrand-containing regions, particularly when oriented in thelongitudinal direction (i.e., parallel to the elastic strands). Theelastic strands would be easily handled prior to separation and couldthen be applied as separate elastic strands by known methods.

The following Examples are provided to illustrate presently contemplatedpreferred embodiments and the best mode for practicing the invention,but are not intended to be limiting thereof.

EXAMPLE 1

A continuous extrusion was carried out using a modified Cleoren™combining adapter such as shown in FIG. 2(a and b). The insert 14 wasprovided with seven outlets 17. The outlets width (1-7) (0.125 in (0.32cm) high) measured, respectively, in inches 0.125 (0.318 cm), 0.313(0.795 cm), 0.250 (0.635 cm), 0.125 (0.318 cm), 0.188 (0.478 cm), 0.375(0.953 cm) and 0.125 (0.318 cm). The middle 5 outlets were spaced 3inches (7.62 cm) apart while the end outlets were 2 inches (5.08 cm)from the next outlet. The veins 15 and 16 had a slight inward bevel atthe rounded upstream portion that tended to create a higher volumetricflow into the central openings. In each sample, the polymeric matrixmaterial was Fina 3576 (Fina Oil and Chemical Co., Deer Park, Tex.)polypropylene. The core material was based on an SEBS (styrene-ethylenebutylene-styrene) block copolymer Kraton™ G1657 (Shell Chemical Co.,Beaupre, Ohio) with varying amounts of additives listed in Table 1below, the remaining material being elastomer.

                  TABLE 1                                                         ______________________________________                                        Sample #  PAMS.sup.1   Pigment Irganox.sup.2                                  ______________________________________                                        A         --           2%      --                                             B         10%          2%      1%                                             C         15%          2%      1%                                             D         10%          2%      --                                             ______________________________________                                         .sup.1 Poly(alphamethyl)styrenes, Amoco 18210 (Amoco Oil Co., Chicago, IL     .sup.2 Irganox 1076 antioxidant (CibaGeigy Co., Hawthorn, NY)            

The polypropylene was extruded from a 48 mm Rheotec™ (Rheotec Extruder,Inc., Verona, N.J.) extruder into the Cloeren™ (Cloeren Co., Orange,Tex.) die. The elastomer was extruded from a 2 inch(5.1 cm), 4D ratio,screw diameter Berlyn™ extruder (Berlyn Corp., Worchestor, Mass.). Thematerial was extruded onto a 45° F. (7.2° C.) chrome casting wheelwithout a nip roll. For sample A the Rheotec™ operated at 40 RPM with agear pump at 28 RPM and a head PSI of 1050 (74 kg/cm²). The Berlyn™operated at 5 RPM with no gear pump and a head PSI of 1800 (127 kg/cm²).The Cloeren™ operated at 360° F. (182° C.). Samples B through D operatedat the same conditions except the Rheotec™ screw RPM was 28, its gearpump RPM was 40, and head pressure was 1000 PSI(70 kg/cm²), and theBerlyn™ screw RPM was 4 with a head PSI of 1100 (77 kg/cm²).

The samples produced and their characteristics are shown in Table 2below.

                                      TABLE 2                                     __________________________________________________________________________                                   ELASTIC       OVERALL                          SAM-                                                                              CALIPER (mm)   AVE. CORE/  WIDTH         CALIPER                          PLE SKIN CORE SKIN SKIN RATIO                                                                           INITIAL                                                                            @ NDR                                                                              FINAL                                                                             ELASTIC                                                                            PP    RATIO                                                                             COMMENTS               __________________________________________________________________________    A   0.046 mm                                                                           0.036 mm                                                                           0.064 mm                                                                           0.65   9 mm 9 mm 9 mm                                                                              0.178 mm                                                                           0.099 mm                                                                            1.79                                                                              stretch in PP              0.018                                                                              0.112                                                                              0.020                                                                              5.87   10   37   12  0.152                                                                              0.089 1.71                                                                              elastic                    0.023                                                                              0.089                                                                              0.020                                                                              4.12   11   38   13  0.130                                                                              0.097 1.34                                                                              elastic                    0.020                                                                              0.076                                                                              0.020                                                                              3.75   17   58   21  0.137                                                                              0.102 1.35                                                                              elastic                    0.031                                                                              0.076                                                                              0.036                                                                              2.31   12   51   51  0.163                                                                              0.099 1.64                                                                              stretch in PP and                                                             elastic                B   0.033 mm                                                                           0.056 mm                                                                           0.046 mm                                                                           1.42   14 mm                                                                              14 mm                                                                              14 mm                                                                             0.140 mm                                                                           0.089 mm                                                                            1.57                                                                              stretch in PP              0.028                                                                              0.091                                                                              0.031                                                                              2.78   15   58   20  0.145                                                                              0.097 1.50                                                                              elastic                    0.020                                                                              0.122                                                                              0.036                                                                              4.00   8    25   9   0.155                                                                              0.099 1.56                                                                              elastic                    0.028                                                                              0.097                                                                              0.023                                                                              3.80   11   35   13  5.5  3.0   1.83                                                                              elastic                    0.046                                                                              0.076                                                                              0.033                                                                              1.94   12   12   12  0.155                                                                              0.081 1.91                                                                              stretch in PP          C   0.056 mm                                                                           0.069 mm                                                                           0.036 mm                                                                           1.50   14 mm                                                                              56 mm                                                                              56 mm                                                                             0.155 mm                                                                           0.099 mm                                                                            1.56                                                                              non retraction             0.018                                                                              0.091                                                                              0.018                                                                              5.14   18   61   23  0.145                                                                              0.104 1.39                                                                              elastic                    0.023                                                                              0.089                                                                              0.031                                                                              3.33   10   32   12  0.155                                                                              0.107 1.45                                                                              elastic                    0.023                                                                              0.089                                                                              0.025                                                                              3.68   13   38   15  0.145                                                                              0.086 1.68                                                                              elastic                    0.051                                                                              0.079                                                                              0.038                                                                              1.77   12   12   12  0.163                                                                              0.091 1.78                                                                              stretch in PP          D   0.046 mm                                                                           0.076 mm                                                                           0.051 mm                                                                           1.56   13 mm                                                                              40 mm                                                                              40 mm                                                                             0.160 mm                                                                           0.099 mm                                                                            1.62                                                                              no retraction              0.018                                                                              0.079                                                                              0.018                                                                              4.43   17   62   22  0.142                                                                              0.099 1.44                                                                              elastic                    0.025                                                                              0.089                                                                              0.025                                                                              3.40   10   32   12  0.147                                                                              0.104 1.41                                                                              elastic                    0.023                                                                              0.102                                                                              0.018                                                                              5.00   11   42   15  0.140                                                                              0.081 1.72                                                                              elastic                    0.053                                                                              0.058                                                                              0.036                                                                              1.31   11   11   11  0.160                                                                              0.081 1.97                                                                              stretch in             __________________________________________________________________________                                                           PP                 

The caliper of the matrix skin and core materials was measured using anoptical microscope at the center of each elastic band. The elastic widthwas measured after casting (initial), when stretched (NDR-natural drawratio) and when recovered (final). The overall caliper was measuredusing a micrometer gauge which yielded numbers generally slightly higherthan the combined optical microscope readings for the matrix skin andcore. The PP matrix was measured adjacent to the elastic band, usually1/8 to 1/4 inchs (0.32-0.64 cm) away. The location where the filmyielded when stretched varied. Where the core to skin ratio was lessthan 2.5 and the overall caliper ratio was over 1.5, the film eitherstretched in the polypropylene matrix field of the film or would notrecover when stretched in the Kraton™ core containing zones. It isbelieved that a higher overall caliper ratio contributes significantlyto the stretching of the polypropylene matrix field. A low core/skincaliper ratio will make the material non-recoverable if stretched in thecore containing region. All the samples in Table 1 were stretched in adirection perpendicular to M.D. (machine direction).

EXAMPLE 2

A continuous coextrusion was carried out on the apparatus described inExample 1. The screw speed of the Rheotec™ was set at 28.0 with the gearpump at 45 RPM and the head PSI at 1000. The screw speed of the Berlyn™was set at 4 RPM with a head PSI of 2000 (140 kg/cm²). The polymermatrix was a Shell 7C50 (Shell Chemical Co., Beaupre, Ohio)polypropylene. The elastomeric core material for the four samples A-Dcorresponded to that of samples A-D, respectively, of Example 1. Thesamples were tested in a manner identical to the testing performed onsamples A-D of Example 1 and the results are shown in Table 3.

                                      TABLE 3                                     __________________________________________________________________________                                   ELASTIC       OVERALL                          SAM-                                                                              CALIPER (mm)   AVE. CORE/  WIDTH         CALIPER                          PLE SKIN CORE SKIN SKIN RATIO                                                                           INITIAL                                                                            @ NDR                                                                              FINAL                                                                             ELASTIC                                                                            PP    RATIO                                                                             COMMENTS               __________________________________________________________________________    A   0.056 mm                                                                           0.041 mm                                                                           0.036 mm                                                                           0.89   10 mm                                                                              10 mm                                                                              10 mm                                                                             0.168 mm                                                                           0.089 mm                                                                            1.89                                                                              stretch in PP              0.018                                                                              0.089                                                                              0.020                                                                              4.67   12   40   14  0.142                                                                              0.094 1.51                                                                              elastic                    0.015                                                                              0.127                                                                              0.023                                                                              6.67   11   38   13  0.140                                                                              0.114 1.22                                                                              elastic                    0.020                                                                              0.086                                                                              0.028                                                                              3.58   18   63   24  0.145                                                                              0.109 1.33                                                                              elastic                    0.028                                                                              0.086                                                                              0.043                                                                              2.43   13   40   33  0.165                                                                              0.107 1.55                                                                              bit retraction         B   0.033 mm                                                                           0.071 mm                                                                           0.048 mm                                                                           1.75   13 mm                                                                              36 mm                                                                              28 mm                                                                             0.150 mm                                                                           0.102 mm                                                                            1.48                                                                              bit retraction             0.028                                                                              0.076                                                                              0.033                                                                              2.50   15   52   21  0.152                                                                              0.104 1.46                                                                              elastic                    0.020                                                                              0.109                                                                              0.023                                                                              5.08   8    29   10  0.163                                                                              0.104 1.56                                                                              elastic                    0.033                                                                              0.084                                                                              0.023                                                                              3.00   10   38   13  0.147                                                                              0.086 1.71                                                                              elastic                    0.058                                                                              0.061                                                                              0.036                                                                              1.30   10   10   10  0.152                                                                              0.086 1.76                                                                              stretch in PP          C   0.053 mm                                                                           0.066 mm                                                                           0.020 mm                                                                           1.79   11 mm                                                                              11 mm                                                                              11 mm                                                                             0.165 mm                                                                           0.089 mm                                                                            1.71                                                                              stretch in PP              0.028                                                                              0.097                                                                              0.0234                                                                             3.80   11   40   13  0.158                                                                              0.086 1.71                                                                              elastic                    0.020                                                                              0.114                                                                              0.018                                                                              6.00   9    30   1o  0.163                                                                              0.109 1.44                                                                              elastic                    0.018                                                                              0.094                                                                              0.023                                                                              4.62   16   62   22  0.152                                                                              0.107 1.40                                                                              elastic                    0.038                                                                              0.076                                                                              0.031                                                                              2.22   13   40   27  0.163                                                                              0.102 1.50                                                                              bit retraction         D   0.053 mm                                                                           0.084 mm                                                                           0.036 mm                                                                           1.89   13 mm                                                                              43 mm                                                                              43 mm                                                                             0.165 mm                                                                           0.104 mm                                                                            1.59                                                                              no retraction              0.033                                                                              0.097                                                                              0.023                                                                              3.45   16   56   21  0.158                                                                              0.104 1.5l                                                                              elastic                    0.028                                                                              0.102                                                                              0.028                                                                              3.64   9    29   10  0.163                                                                              0.104 1.56                                                                              elastic                    0.020                                                                              0.109                                                                              0.018                                                                              5.73   10   35   13  0.152                                                                              0.081 1.88                                                                              elastic                    0.061                                                                              0.058                                                                              0.041                                                                              1.15   9    9    9   0.163                                                                              0.079 2.06                                                                              stretch in             __________________________________________________________________________                                                           PP                 

Similar results to that seen in Example 1 were noticed.

EXAMPE 3

In this continuous coextrusion, the operating conditions of theapparatus were a variation of those of Example 1, Sample A, with theRheotec™ screw speed increased to 45 RPM and the head PSI increased to1050 (74 kg/cm²). The RPM of the Berlyn™ was reduced to 4, and the headPSI to 1200 (84 kg/cm²). The sample compositions A-D were identical tothose of samples A-D of Example 1 except that Kraton™ 1107(styrene-isoprene-styrene) was used as the elastomer.

The extrusion and stretching results for each strand are shown in Table4 (tested as in Examples 1 and 2).

                  TABLE 4                                                         ______________________________________                                                                   Ave.                                                                          Core/                                                                              Initial                                                                             Final                                   Sam-         Caliper (mm)  Skin Elastic                                                                             Elastic                                 ple  Skin    Core    Skin  Ratio                                                                              Width Width Comments                          ______________________________________                                        A    0.028   0.089   0.056 2.12 12 mm 51    no                                                                            retraction                             0.015   0.079   0.025 3.88 17    19    elastic                                0.028   0.103   0.023 4.00  9    11    elastic                                0.023   0.107   0.025 4.42 12    13    elastic                                0.051   0.081   0.041 1.78 11    11    stretch in                                                                    PP                                B    0.036   0.066   0.031 2.00 14 mm 36    no                                                                            retraction                             0.018   0.091   0.023 4.50 15    16    elastic                                0.020   0.086   0.025 3.78 12    12    elastic                                0.023   0.061   0.028 2.40 21    26    elastic                                0.036   0.079   0.041 2.07 15    58    no                                                                            retraction                        C    0.028   0.086   0.033 2.83 16 mm 58    no                                                                            retraction                             0.015   0.091   0.018 5.54 19    24    elastic                                0.025   0.089   0.023 3.68 11    11    elastic                                0.020   0.084   0.031 3.30 14    16    elastic                                0.038   0.069   0.025 2.16 14    60    no                                                                            retraction                        D    0.043   0.064   0.036 1.61 14 mm 46    heat                                                                          shrink                                 0.028   0.107   0.031 3.65 17    23    elastic                                0.031   0.099   0.025 3.55 15    18    elastic                                0.020   0.119   0.015 6.71 26    33    elastic                                0.041   0.091   0.036 2.40 16    70    no                                                                            retraction                        ______________________________________                                    

As can be seen, Sample D demonstrated heat shrink characteristics at lowcore/skin ratios.

EXAMPLE 4

These continuous coextrusion samples A-D had identical compositions tothose of samples A-D of Example 2. Properties of the film are shown inTable 5 (tested as above). Sample E is identical to sample D except thatthe elastomer component contained 2% white pigment. Both heat and timeshrink samples were noted. The shrink mechanisms were determined at roomtemperature (25° C.).

                  TABLE 5                                                         ______________________________________                                                                   Ave.                                                                          Core/                                              Sam-         Caliper (mm)  Skin Elastic                                                                             Width                                   ple  Skin    Core    Skin  Ratio                                                                              Initial                                                                             Final Comments                          ______________________________________                                        A    0.48    0.064   0.038 1.47 12 mm 47 mm no                                                                            retraction                             0.043   0.097   0.031 2.62 12    15    elastic                                0.028   0.122   0.025 4.57  6     7    elastic                                0.031   0.122   0.025 4.36  9    10    elastic                                0.031   0.089   0.058 2.00 12    53    no                                                                            retraction                        B    0.020   0.074   0.033 2.76 4 mm  17 mm no                                                                            retraction                             0.028   0.091   0.025 3.43 15    39    time                                                                          shrink                                 0.025   0.107   0.028 4.00 12    13    elastic                                0.020   0.102   0.028 4.21  8    10    elastic                                0.018   0.125   0.018 7.00 17    20    elastic                                0.028   0.097   0.025 3.62 16    36    time                                                                          shrink                                 0.023   0.069   0.028 2.70  5    19    no                                                                            retraction                        C    0.025   0.076   0.028 2.86 15 mm 60    slight                                                                        retraction                             0.23    0.081   0.025 3.37 12    15    elastic                                0.031   0.107   0.028 3.65  8    10    elastic                                0.023   0.099   0.023 4.33 16    19    elastic                                0.033   0.081   0.028 2.67 16    40    time                                                                          shrink                            D    0.023   0.086   0.056 2.19  6 mm 15 mm slight                                                                        retraction                             0.031   0.081   0.031 2.67 16    24    time                                                                          shrink                                 0.018   0.137   0.023 6.75 17    21    elastic                                0.028   0.107   0.031 3.65  9    10    elastic                                0.031   0.099   0.028 3.39 13    14    elastic                                0.031   0.086   0.031 2.83 16    25    time                                                                          shrink                                 0.036   0.056   0.031 1.69  6    20    bit                                                                           retraction                        E    0.033   0.081   0.040 2.21 16 mm       slight                                                                        retraction                             0.023   0.122   0.028 4.80 13          elastic                                0.031   0.147   0.038 4.30  9          elastic                                0.025   0.097   0.025 3.80 17          elastic                                0.036   0.091   0.038 2.48 16          time                                                                          shrink                            ______________________________________                                    

EXAMPLE 5

The insert was provided with 1/16 in. (0.158 cm) wide, 0.125 in. (0.32cm) high holes spaced 1/16 in(0.158 cm) apart. The elastic core materialwas 99% Kraton™ 1107 (and 1% antioxidant fed by a 2 inch (5.08 cm)Berlyn™ extruder with zone temperatures varied from 280° F. (138° C.) to400° F. (204° C.) at the exit, operating at 15 rotations per minute(RPM). The matrix material was a linear low density polyethylene,Dowlex™ 2517 (Dow Chem. Co., Rolling Meadows, Ill.) fed by a 1 in (2.54cm) Brabender™ (C. W. Brabender Instruments, Inc., N.J.) extruderoperating at 43 RPM and with zone temperatures ranging from 145° C. to173° C., at the exit. The die and casting roll operated at 360° F. (182°C.) and 70° F. (21° C.), respectively, with the casting roll running at11.1 and 16.8 ft (3.4 and 5.12 m/min) for samples A and B.

For sample C, the Berlyn™ extruder was run at the same conditions exceptthe inlet zone was set at 285° F. (141° C.), and it ran at 30 RPM. Thematrix material was changed to polypropylene (PP 3014) (Exxon Chem.Corp., Houston, Tex.) and run at 20 RPM in the Brabender™ (zonetemperature ranging from 165° C. to 223° C.). The die and casting rollswere 400° F. and 66° F. (204° C. and 19° C.), respectively, with a rollspeed of 11.5 feet (3.5 meters) per minute.

The dimensions of the material (mils and (mm)) obtained are shown inTable 6 below.

                  TABLE 6                                                         ______________________________________                                              Total     Thickness        Space                                        Sample                                                                              Thickness Between  Height  Width  Between                               #     at Core   Cores    Core    Core   Cores                                 ______________________________________                                        A     19 (.48)    4 (0.01)                                                                             17.2(0.44)                                                                             40(1.01)                                                                            100(2.54)                             B     10 (0.25) 1.2 (0.03)                                                                             9.2(0.23)                                                                              24(0.61)                                                                             92(2.34)                             C       5.6 (0.14)                                                                            5.2 (0.13)                                                                             4.8(0.12)                                                                             114(2.90)                                                                            116(2.95)                             ______________________________________                                    

The materials were all stretched 5:1 and allowed to relaxinstantaneously. FIG. 8 is a scanning electron micrograph of thestretched and relaxed sample B. FIGS. 6 and 7 are scanning electronmicrographs of sample C, stretched uniaxially in the cross direction andmachine direction, respectively. All the films show regular or periodicfolding when stretched in the machine direction. In samples A and B, thethickness of the matrix material between the cores 7 appeared to be dueto the low die swell of the matrix material compared to the Kraton™elastomeric core material. In all films, the matrix material completelycircumscribed the cores 7 with only the cut end of each film havingexposed core material.

In sample C, the die swell of the core and matrix materials were verysimilar and the film formed had a relatively flat profile. The corematerial in sample C was also fed at a considerably higher relativerate, to the matrix in sample C, as compared to samples A and B,resulting in a considerably larger elastomeric core region.

EXAMPLE 6

In this example, samples A-C were identical compositionally to sample Cof Example 5. The Berlyn™ extruder was run at 10 RPM (zone temperaturesranging from 370° F. (188° C.) to 420° F. (216° C.). The matrix wasextruded from a 2 in. (5.08 cm) Rheotec™ extruder (zone temperaturesranging from 350° F. (177° C.) to 400° F. (204° C.), operating at 61 RPMwith a 400° F. gear pump at 50 RPM. The die was at 400° F. (204° C.)feeding onto a 50° F. (10° C.) casting roll operating at 54.1, 38.8 and33.0 ft (16.5, 11.8 and 10.1 m) per minute for samples A-C,respectively.

Sample D was run using the Brabender™ extruder for the elastic (zonetemperature range 380°-420° F. (193°-216° C.)) with the same elastic.The matrix was run on the above Rheotec™ arrangement with the gear pumpat 20 RPM. The matrix was 90% PP 8771 (Exxon Chem. Corp.) with 10% bluepigment. The casting roll was 50° F. (10° C.) and ran at 21.4 ft (12.2m) per minute.

Sample E was run the same as D, except the gear pump ran at 40 ft (12.2m) per minute, the Brabender™ at 32 RPM and the casting roll ran at 40ft (12.2 m) per minute.

Sample F was run the same as E except the casting roll ran at 23.3 ft(7.1 m) per minute.

Sample G was run the same as F except the casting roll ran at 21.4 ft(6.5 m) per minute, and the matrix was 50% polybutylene (PB 8010available from Shell Chem. Co., Beaupre, Ohio), 40% polypropylene (PP3014 available from Exxon Chem. Co., Houston, Tex.) and 10% bluepigment.

Sample H was run the same as F except the skin was 70% PP 3014, 20% PB8010 and 10% blue pigment.

The insert for this example had holes 0.125 in (0.32 cm) high, and 0.5in (1.27 cm) wide with 4 in (10.16 cm) between holes.

The dimensions of the samples are set forth in Table 7 below, in mils(mm).

                                      TABLE 7                                     __________________________________________________________________________    Sample                                                                            Total Thickness                                                                       Thickness Between                                                                      Height                                                                            Width                                                                              Space Between                                   Number                                                                            at Core Cores    Core                                                                              Core Cores                                           __________________________________________________________________________    A   3.5(0.089)                                                                            3.0(0.076)                                                                             --  1.4(0.036)                                                                         2.0(0.051)                                      B   4.3(0.11)                                                                             4.2(0.11)                                                                              --  1.5(0.038)                                                                         2.0(0.051)                                      C   5.1(0.13)                                                                             5.1(0.13)                                                                              --  1.4(0.036)                                                                         2.0(0.051)                                      D   8.0(0.18)                                                                             7.0(0.18)                                                                              --  1.1(0.028)                                                                         2.4(0.061)                                      E   4.2(0.11)                                                                             3.4(0.088)                                                                             --  1.0(0.025)                                                                         2.3(0.055)                                      F   4.3(0.11)                                                                             3.6(0.091)                                                                             --  0.9(0.023)                                                                         2.1(0.053)                                      G   3.7(0.094)                                                                            3.9(0.099)                                                                             --  1.3(0.033)                                                                         2.0(0.051)                                      H   5.5(0.014)                                                                            5.0(0.127)                                                                             --  1.0(0.025)                                                                         2.1(0.053)                                      __________________________________________________________________________

These samples were all stretched 5:1 in the machine direction andrelaxed instantaneously.

EXAMPLES 7 and 8

Samples B and C of Example 5 were coated with adhesive and wereidentified as Examples 7 and 8, respectively. Example 7 was coated witha hot-melt coatable, pressure-sensitive adhesive comprising a tackifiedsynthetic block copolymer. Example 8 was laminated to a 37.5 mil thickacrylate adhesive (3M 9671 SL). Both tapes were formed by applying theadhesive prior to stretching the backing. Tape 7 was adhered to itselfand a glass plate after stretching in the machine direction. Tape 8 wasalso adhered to itself and a glass plate after stretching in the machineand cross directions. All the tapes were stretched uniaxially at a 5:1draw ratio. The tapes were peel tested at 90 degree and 180 degree peelangles, after adhering with a 5 lb rolldown (1 minute dwell), at a peelrate of 90 in/min (5 second average value). The results are shown inTable 8 below in gm/in. "Flat" indicates the film prior to stretchingand "Stretched" indicates the film after stretching and recovery. Tapes7 and 8 (MD) tore in the machine direction.

                  TABLE 8                                                         ______________________________________                                                    Example                                                                       7         8 (MD)  8 (CD)                                          ______________________________________                                        Adhesion to Glass                                                             180° Flat                                                                            1,690       336     540                                         180° Stretched                                                                       561         312     317                                         90° Flat                                                                             544         333     463                                         90° Stretched                                                                        264         168     213                                         Adhesion to Backside                                                          180° Flat                                                                            360         207     309                                         180° Stretched                                                                       456         212     125                                         90° Flat                                                                             286         208     266                                         90° Stretched                                                                        140         120     191                                         ______________________________________                                    

For Examples 7 and 8(MD), the 180 degree Stretched Adhesion to Backsidewas higher than to the Flat Adhesion to Backside peel indicating thatthere was likely inter-penetration of the macrostructure folds of theadhesive and the macrostructure folds of the backside.

The various modifications and alterations of this invention will beapparent to those skilled in the art without departing from the scopeand spirit of this invention, and this invention should not berestricted to that set forth herein for illustrative purposes.

We claim:
 1. A continuous nonwoven film laminate comprising at least onefibrous nonwoven layer laminated to a coextruded film comprising atleast one discrete elastomeric core containing region capable of elasticelongation and a matrix of thermoplastic polymeric material, whichpolymeric matrix material is less elastic than the elastomeric corematerial, said matrix material completely circumscribing said at leastone discrete elastomeric core so that there is at least two nonelasticfilm regions comprising nonelastic matrix material, wherein thethickness and the presence of the elastomeric core material variesacross the film length and/or width and wherein said coextruded film hasbeen stretched in the transverse direction past the inelasticdeformation limit of the matrix material around said at least oneelastomeric core to form a microtextured skin layer, formed of thematrix material over the at least one elastomeric core, only in theelastomeric core containing region of said film, said laminate isextensible in the transverse direction and nonextensible in thelongitudinal direction.
 2. The continuous nonwoven film laminate ofclaim 1 wherein the at least one elastomeric core comprises anextrudable polymer and said matrix material is a thermoplastic polymer.3. The continuous nonwoven film laminate of claim 1 wherein the fibrousnonwoven layer is extended in the elastomeric core containing region ofthe film and nonextended in the nonelastic region of the film whereinthe laminate is extensible and elastic in the transverse direction. 4.The continuous nonwoven film laminate of claim 1 wherein the fibrousnonwoven layer is nonextended in the elastomeric core containing regionof the film.
 5. The continuous nonwoven film laminate of claim 4 whereinthe laminate is extensible and elastic in the transverse direction. 6.The continuous nonwoven film laminate of claim 4 wherein the laminate isextensible and nonelastic in the transverse direction and furtherwherein when said laminate is stretched in the transverse direction thelaminate will stretch in the elastic region of the film and recover toform an laminate that is extensible and elastic in the transversedirection.
 7. The continuous nonwoven film laminate of claim 1 whereinthe fibrous nonwoven layer is heat or sonicly bonded to the coextrudedfilm.
 8. The continuous nonwoven film laminate of claim 1 wherein thefibrous nonwoven layer is adhesively bonded to the coextruded film. 9.The continuous nonwoven film laminate of claim 1 wherein the fibrousnonwoven layer is extrusion laminated to the coextruded film.